Vacuum seed meters are commonly used in agricultural planters in the planting of crops. The typical vacuum seed meter includes a rotating seed disc having plural spaced apertures about its periphery. Each aperture is adapted to receive an individual seed which is maintained in position in the aperture on a first side of the seed disc by means of a vacuum applied to a second, opposed sided of the disc. Each seed is sequentially released from its aperture in the seed disc by interrupting the applied vacuum, allowing the seed to drop to the soil under the influence of gravity.
Vacuum seed meters have, to varying degrees, various operating limitations because of their design and the environment in which they operate. For example, a high vacuum must be maintained across the seed disc to securely maintain the seeds in position on the seed disc until they are released. The applied vacuum must be interrupted completely and very abruptly to allow for the consistent and accurate release of the individual seeds to ensure proper seed positioning and inter-seed spacing. Irregularities in seed position and inter-seed spacing result in poor plant development and reduced crop production. Failure to maintain a vacuum seal in the seed meter results in variations in the applied vacuum and introduction of crop residue or various other unwanted remnants, any of which can cause irregular and inconsistent seed meter performance, and damage to or failure of the seed meter. Maintaining a high vacuum requires fixed seals between adjacent stationary components and intimate contact between adjacent moving components. Intimate contact between moving parts gives rise to component wear, formation of gaps between these moving parts over time, and a consequent reduction in the performance of the seed meter. In addition, frictional losses in many existing vacuum seed meters imposes substantially increased loads on the source of power for these types of agricultural implements, i.e., the tractor.